1. Field of the Invention
The present invention relates to an electric rotating machine and a manufacturing method thereof, and relates to an electric rotating machine such as a turbine generator and the like for example, which is preferable for those provide with a connecting line which connects a conductor for supplying electricity from the outside and an end portion of a rotor winding, and a manufacturing method thereof.
2. Description of Related Art
A generator used in power generating equipment including a gas turbine or a steam turbine as a driving source generates electric power by mutual electromagnetic induction between a rotor and a stator. In general, a rotor winding is formed by a plurality of conductors wound thereon for producing an induction field, and a magnetic flux is generated by electrifying the winding. Accordingly, the rotor winding requires a conductor for supplying electricity from the outside of the generator, and this conductor is generally provided in a center portion of a rotor body, and the conductor and an end portion of the rotor winding are connected by a connecting line. The connecting line is generally designed to have a bending portion for the purpose of relieving deformation caused by the difference in thermal extension due to the difference in material between the conductor and the rotor body, and by a centrifugal force (see U.S. Pat. No. 5,122,696, for example).
For the meantime, by technological advance in recent years, the size of an electric rotating machine having the same output becomes more compact than before, the output per unit volume increases, and correspondingly, the rise in temperature of a current-carrying part tends to be large. Therefore, it is the mainstream to apply an iron material to the rotor and apply a copper material to the rotor winding, however, the thermal extension difference caused by current applied during operation occurs due to the difference in physical properties between those.
Thus, in order to prevent each component member from breaking due to fatigue in strength, a mechanism for absorbing the thermal extension is required for applying it to an actual machine. Particularly, since a generator of which the drive source is a gas turbine or a steam turbine is operated generally at 1500 to 3600 rpm in a steady state, a rotor having a rotary shaft of which the length is larger than its diameter is adopted in view of a limitation of strength due to a centrifugal force. Further, a rotor wining of the generator is often equipped with a conductor wound in a number of layers in a rectangular shape and has its longitudinal direction in a rotor axial direction, and therefore, the thermal extension direction conspicuously appears in the axial direction.
Further, for preventing the rotor winding from protruding in a radial direction by its rotation, it is general to provide a rotor body part with a wedge, and provide a rotor end portion with a retaining ring. However, since the retaining ring bellies out in the radial direction during rotation due to a hoop force, the end portion of the rotor winding located directly under there also bellies out toward an outside diameter side in the same manner.
On the other hand, a conductor is provided in an axial center portion of the rotor and is connected with the external power supply for electrifying the rotor winding, and a conductor support pillar attached to this conductor and the end portion of the rotor winding are electrically connected by a connecting line (lead). This connecting line is repeatedly affected by the above described thermal extension in the axial direction and by the displacement in the outside diameter direction by a centrifugal force, at each actuation and stoppage.
As the structure which absorbs an operating force by this displacement, U.S. Pat. No. 5,122,696 proposes a connecting line which provides a space by connecting two conductors having the structure of a T shape having a bent portion. Since a coil surface on which the connecting line is mounted differs in radial direction position from another coil surface, the structure of a main body of the connecting line forms the T shape in order to absorb the displacement in the outside diameter direction by a centrifugal force. The conductor at the bent portion space of the T-shaped structure is constructed by a thin single conductor, and has a second T-shaped conductor inside the above described T-shaped conductor in combination, for the purpose of reinforcement.